Joint Optimal and Adaptive 2-D Spatial Filtering Technique for FDA-MIMO SAR Deception Jamming Separation and Suppression

The existence of mainlobe deception jamming may seriously affect the information reconnaissance of synthetic aperture radar (SAR), resulting in unpredictable misjudgment. The similarity between deception jamming and real target scene in multiple domains brings excellent challenges to jamming detection and suppression. We find that the additional degrees of freedom (DOFs) brought by the multiple-input multiple-output (MIMO) frequency diversity array (FDA) system have unique advantages in solving this problem. Analysis proved that the coupling relationship of 2-D transmit-receive spatial frequency for the real target scene and the deception jamming is different. The 2-D transmit-receive spatial domain distribution of the real scene can be determined by the geometric configuration, while the distribution of deception jamming is inconsistent with the geometric position of the false targets due to the additional modulation. We proposed a joint optimal and adaptive 2-D spatial filtering technique based on this characteristic. The range-dependent phase of the echo is first compensated to separate the deception jamming from the real scene in the 2-D transmit-receive spatial domain. Then, jamming detection and localization are performed on the 2-D transmit-receive spatial spectrum. Adaptive covariance matrix estimation of the real target scene is performed from the range cells with no jamming detected. Afterward, the 2-D spatial filter is designed by solving a constrained optimization problem (COP) using the differential evolution (DE) algorithm based on the constrained dominance principle (CDP). Finally, jamming-free SAR imagery is obtained after processing all the pulses. The proposed technique exhibits sufficient performance in deception jamming rejection for SAR images, while the real target scene is almost undistorted. Simulation results are presented to demonstrate the performance of the proposed technique.